An inkjet head is equipped with multiple side walls that are formed by piezoelectric elements with differing polarities that are adhered together one above the other, and electrodes that are installed on these side walls. The side walls change shape elastically due to voltages that are applied to the electrodes. Due to this deformation, the volume of the pressure chamber changes. Due to this change in volume of the pressure chamber, suction and discharge of the ink is performed.
Since there is the possibility that water-soluble ink would be used, there is the necessity to insulate the electrodes. Traditionally, electrodes are coated with, for example, resins typified by paraxylene polymers such as Parylene®. However, the ink can intrude from the edge parts of this resin film and corrode the electrodes.
Regarding this point, technology to place grease on the edge parts of the resin film has been proposed.
However, even with this technology, grease can dissolve in ink if the ink comes in contact with the grease, and there remains the possibility that the ink will come in contact with the electrodes.